Lens cap for optical projectors

ABSTRACT

Various embodiments described herein relates to a lens cap, adapted to be mechanically engaged over a lens assembly of an optical projector. The lens cap, as described herein, is adapted for vignetting a light pattern projected by the optical projector. The lens cap includes a front surface and a back surface, where on at least a portion of the front surface, an elliptically shaped aperture is defined. In this aspect, the elliptically shaped aperture is chamfered towards its peripheral ends, as the elliptically shaped aperture extends out from the back surface of the lens cap towards the front surface of lens cap. Also, the elliptically shaped aperture is defined on the lens cap such that, a center axis of the aperture is offset to a central axis of the lens cap, so as to match an offset at which the light pattern is projected by the optical projector.

BACKGROUND

Generally, optical projectors are used in a variety of environments forprojecting light in a field of view, for different purposes. Forexample, in some cases, these projectors are used for depth sensing of3D objects by casting a pattern of structured light or coded light onthe 3D objects. The optical projector, usually, includes a light source,such as a laser diode or light-emitting diode, to generate opticalradiation, for instance, in the form of a laser beam. In some cases, theoptical radiation may be projected as a pattern on the objects by usingmasking elements or filters or diffracting elements. These opticalprojectors that are adapted to project a light pattern, for example, asa structured light, are also used in object dimensioning systems, havingrange cameras, for three-dimensional (3D) dimensioning of the objects.Applicant has identified a number of deficiencies and problemsassociated with conventional optical projectors. Through applied effort,ingenuity, and innovation, many of these identified problems have beensolved by developing solutions that are included in embodiments of thepresent disclosure, many examples of which are described in detailherein.

BRIEF SUMMARY

Various embodiments of the present disclosure as described herein,relate generally to a structure of a lens cap, particularly, a lens capthat is adapted to be mechanically engaged on a lens assembly of anoptical projector, for example, but not limited to, a light patternprojector.

According to an embodiment, a lens cap having a back surface and a frontsurface, is described. In this regard, the back surface of the lens capis adapted to be mechanically engaged over a light pattern projector.The light pattern projector, as mentioned herein, is adapted to projecta structured light, in a field of view. In accordance with saidembodiment, a portion of the front surface, defines an ellipticallyshaped aperture that is adapted to provide a vignetting on thestructured light projected from the pattern projecting unit.

In accordance with another embodiment, a lens cap is described. The lenscap has a back surface that is adapted to be mechanically engaged over alight pattern projector and a front surface. In this aspect, on aportion of the front surface of the lens cap, an elliptically shapedaperture (opening) is defined. In this regard, the elliptically shapedaperture is adapted to provide vignetting on a light pattern that isprojected from the light pattern projector. In accordance with saidembodiments, a periphery of the elliptically shaped aperture ischamfered, as the aperture extends out from the back surface to thefront surface of the lens cap. The elliptically shaped aperture definesa center of the axis that passes orthogonally through the front surfaceand the back surface of the lens cap and via a point of intersection ofa major axis and a minor axis of the elliptically shaped aperture. Tothis extent, the center axis of the elliptically shaped aperture isoffset from a central axis of the lens cap.

In an aspect, according to said embodiment, a cross-section of theelliptically shaped aperture is adapted to match a field of view of thelight pattern projecting unit, as the lens cap is mechanically engagedover a lens assembly of the light pattern projecting unit. In anotheraspect, according to said embodiments, the elliptically shaped apertureof the lens cap is adapted to at least, block or partially allow,outermost rays which are at periphery of a projected laser beam definingthe projected pattern, as the light pattern projected from a lensassembly of the light pattern projecting unit passes through theelliptically shaped aperture of the lens cap.

In another aspect, according to said embodiment, a length of the majoraxis and a length of the minor axis of the elliptically shaped apertureis based on a defined value to which the projected light pattern isoffset from a center axis of the lens of the light pattern projectingunit. In another aspect, in accordance with said embodiments, a slope ofthe chamfered periphery of the elliptically shaped aperture is based onat least one of: (i) an axial distance between a lens assembly of thelight pattern projecting unit and the back surface of the lens cap and(ii) a corner reduction ratio of the projected pattern, wherein thecorner reduction ratio is representative of a desired percentagedecrease, in intensity of outermost rays of a projected laser beamdefining the projected light pattern.

In accordance with said embodiment, the slope of the chamfered peripheryof the elliptically shaped aperture causes vignetting of the outermostrays of the projected laser beam defining the projected pattern. In thisregard, the offset in the center axis of the elliptically shapedaperture is to match an offset of the projected light pattern projectedby a light source through a lens assembly of the light patternprojecting unit.

According to another embodiment, an imaging system is described. Theimaging system includes a light pattern projecting unit having aprojector lens assembly. In this aspect, the light pattern projectingunit is adapted to project structured light in its field of view. Theimaging system also includes, a lens cap having a front surface and aback surface. In this regard, the back surface is adapted to bemechanically engaged over the projector lens assembly of the lightpattern projecting unit. In an aspect, according to said embodiment, theelliptically shaped aperture is chamfered towards a periphery at whichthe elliptically shaped aperture extends out from the back surface tothe front surface of the lens cap. Also, in an aspect, according to saidembodiment, a center axis, passing orthogonally through the frontsurface and the back surface and via a point of intersection of a majoraxis and a minor axis of the elliptically shaped aperture, is offsetfrom a central axis of the lens cap. In another aspect, according tosaid embodiment, the imaging system further includes an imaging unit,including an image sensor. In this regard, the imaging unit is adaptedto capture an image of a reflection of the structured light, sensed bythe image sensor in a field of view of the imaging unit. In this aspect,(i) a slope of the chamfered periphery of the elliptically shapedaperture causes vignetting of outermost rays of projected laser beamdefining the projected structured light and (ii) the offset in thecenter axis of the elliptically shaped aperture is to match an offset ofthe projected structured light towards a field of view of the imagingunit

The above summary is provided merely for purposes of providing anoverview of one or more exemplary embodiments described herein so as toprovide a basic understanding of some aspects of the disclosure.Accordingly, it will be appreciated that the above-described embodimentsare merely examples and should not be construed to narrow the scope orspirit of the disclosure in any way. It will be appreciated that thescope of the disclosure encompasses many potential embodiments inaddition to those here summarized, some of which are further explainedin the following description and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the illustrative embodiments can be read inconjunction with the accompanying figures. It will be appreciated thatfor simplicity and clarity of illustration, elements illustrated in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements are exaggerated relative to otherelements. Embodiments incorporating teachings of the present disclosureare shown and described with respect to the figures presented herein, inwhich:

FIG. 1 schematically depicts an exemplary environment including a lightpattern projector, in accordance with some embodiments described herein;

FIG. 2 schematically depicts a diagram illustrating an imaging systemincluding a light pattern projector, in accordance with some exampleembodiments described herein;

FIG. 3 illustrates an exemplary environment depicting implementation ofan imaging system including the light pattern projector over which alens cap can be mechanically engaged, in accordance with some exampleembodiments described herein;

FIG. 4 schematically illustrates an exploded perspective view of thelight pattern projector adapted to be mechanically engaged with a lenscap, in accordance with various example embodiments described herein;

FIG. 5 schematically illustrates a perspective view of a lens capmechanically engaged to a lens assembly of a light pattern projector, inaccordance with one example embodiment described herein;

FIG. 6 schematically illustrates front and back surfaces of a lens cap,in accordance with one example embodiment described herein.

FIG. 7A schematically illustrates an arrangement representing a lens caphaving a cylindrically shaped back casing, where the lens cap ismechanically engaged to a lens assembly of a light pattern projector, inaccordance with another example embodiment described herein;

FIG. 7B schematically illustrates an arrangement representing the lenscap having the cylindrically shaped back casing, where the lens cap ismechanically dis-engaged from the lens assembly of the light patternprojector, in accordance with another example embodiment describedherein;

FIG. 8 schematically illustrates front view of the lens cap mechanicallyengaged over the lens assembly of the light pattern projector, inaccordance with another example embodiment described herein;

FIG. 9 illustrates a side view of the lens cap mechanically engaged overthe projector lens assembly of the light pattern projector, inaccordance with some example embodiments described herein.

FIG. 10 illustrates multiple perspective views of the lens cap,representing different surfaces of the lens cap having the cylindricallyshaped back casing, in accordance with some embodiments describedherein.

FIGS. 11A and 11B illustrates structures of front surface and backsurface of the lens cap, in accordance with one example embodimentdescribed herein;

FIGS. 12A and 12B schematically illustrates structures of a frontsurface and back surface respectively of a lens cap having acylindrically shaped back casing, in accordance with some exampleembodiments as described herein.

FIG. 13 schematically illustrates alignment features adapted to be usedfor mechanically engaging a lens cap over a lens assembly of a lightpattern projector, in accordance with some embodiments described herein.

FIGS. 14A-14B schematically illustrates multiple cut-away perspectiveviews of a light pattern projector having lens cap mechanically engagedover a lens assembly of the projector, where the light pattern projectoris adapted to project a light pattern that is spatially offset in onedirection, in accordance with some embodiments described herein;

FIG. 14C schematically illustrates a side view of a light patternprojector having lens cap mechanically engaged over a lens assembly ofthe projector, where the light pattern projector is adapted to project alight pattern that is spatially offset in one direction, in accordancewith some embodiments described herein;

FIGS. 14D and 14E schematically illustrates multiple perspective viewsof a lens cap mechanically engaged over the light pattern projector thatis adapted to project a light pattern spatially offset in one directionwith respect an axis of a lens assembly of the light pattern projector,in accordance with some example embodiments described herein;

FIG. 15 schematically illustrates vignetting of outermost rays ofoptical radiation such as, a light pattern, by using a lens cap alongwith a light pattern projector, in accordance with some embodimentsdescribed herein.

FIG. 16A and 16B, schematically illustrates, simulation resultsincluding, results depicting illumination of a surface with vignettingby using the light pattern projector with lens cap, as compared to,results depicting illumination of a surface by using the light patternprojector without lens cap, in accordance with various embodimentsdescribed herein;

DETAILED DESCRIPTION

Some embodiments of the present disclosure will now be described morefully hereinafter with reference to the accompanying drawings, in whichsome, but not all embodiments of the disclosure are shown. Indeed, thesedisclosures may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements. Like numbers refer to like elements throughout.Terminology used in this patent is not meant to be limiting insofar asdevices described herein, or portions thereof, may be attached orutilized in other orientations.

The phrases “in one embodiment,” “according to one embodiment,” and thelike generally mean that the particular feature, structure, orcharacteristic following the phrase may be included in at least oneembodiment of the present disclosure, and may be included in more thanone embodiment of the present disclosure (importantly, such phrases donot necessarily refer to the same embodiment).

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations.

If the specification states a component or feature “may,” “can,”“could,” “should,” “would,” “preferably,” “possibly,” “typically,”“optionally,” “for example,” “often,” or “might” (or other suchlanguage) be included or have a characteristic, that particularcomponent or feature is not required to be included or to have thecharacteristic. Such component or feature may be optionally included insome embodiments, or it may be excluded.

The term “object” as used herein may correspond to a physical item,element, device, or the like that is present in a scene. For example, awarehouse or a retail outlet (e.g., a scene) may include objects,parcels, cartons, shipping containers, and/or the like. In someexamples, the object may be a static object or a dynamic object. Thestatic object in a scene may correspond to an object which remainssubstantially stationary over a period of time. For example, staticobjects in a warehouse may include structural support elements, such aspillars, walls, and/or the like of the warehouse. A dynamic object maycorrespond to an object with a location in the warehouse that is notfixed. For example, the location of one or more parcels in warehouse maynot be fixed, as the one or more parcels may be shipped-in, shipped-out,or otherwise moved in the warehouse (e.g., scene).

Usually, while designing and manufacturing optical projectors, inaddition to along with consideration given for internal assembling ofcomponents and structure of the optical projectors, consideration isgiven to power output levels and maintaining intensity of opticalradiation, at which the optical projector projects light. Also, mostlyin environments that include imaging systems, for example multiplecameras and image processors, light pattern projectors may be used forilluminating various objects to identify three-dimensional (3D) objectsin a field of view and/or to compute dimensions of the objects. Suchlight pattern projectors, usually, include a high-power light source,for instance, a vertical-cavity surface-emitting laser (VCSEL) lasersource or laser diode along with a pattern masking element, forprojecting a structured light, i.e. a pattern of light or opticalradiation in coded or known pattern form, on an object. In systems, forexample, warehouses or distribution centers, where such patternprojectors are used along with imagers, for example, one or morecameras, the pattern projectors are used to project the structured lighton an object that is to be dimensioned. The reflection of the structuredlight from the object is realized in a field of view of the one or morecamera units, which thereafter captures its images for computing thedimensions of the object.

Designing such light pattern projectors, requires optical emission, forexample, laser beam emission from a light source of the patternprojectors, to meet safety standards of laser emissions, as prescribedby various agencies (e.g., European Norm (EN) 207, American NationalStandards Institute (ANSI) Z136, and/or the like). Accordingly, whiledesigning the light pattern projectors, it is often considered that, inoperation, the light pattern projected from a light pattern projector isof uniform intensity and within permissible safety radiation limits, asit is projected on a plane surface (e.g., a projection screen). However,safety standards of laser emissions are evaluated based on the intensityof the light pattern a predefined distance from the projectors (e.g., ona spherical surface). As, usually, these light pattern projectors aredesigned to provide a uniform intensity light pattern on a flat screen(i.e. surfaces where edges of a screen surface are farther from theprojector than a center of the screen surface), the light rays definingthe light pattern towards its edges have increased intensity/lightoutput level, as compared to, intensity values of light rays of thepattern profile, which are towards center of the projected lightpattern. To this extent, when the projected light pattern is evaluatedat a spherical surface, in various scenarios it is observed that theintensity of optical radiation defining the edges of the projected lightpattern surpasses laser safety standards while the central portion ofthe projected light pattern is safely within the laser safety standards.

To this extent, some existing techniques used for controlling and/orreducing intensity/output level of light projectors require, customizinga masking element of the light pattern projector, for example, with agrey scale pattern that matches a mask transmittance distribution of themasking element with a desired energy distribution. However, suchtechniques are usually costly when compared to using a standard binarymasking element in the light pattern projectors. Also, controllingillumination quality of the projectors, while using such maskingelements, is challenging. Alternatively, some other existing approachesrely on performing structural changes to lens and other elements of thelight pattern projector assembly. However, such structural changes alsodo not provide effective control over a desired power output level.Further, in imaging systems where light patterns are projected at anoffset towards an imaging unit, such internal changes in the projectorlens assembly, often causes sharp decrease in intensity level ofprojection towards one side of a profile of the light pattern, thereby,reducing an overall performance in entire field of view of theprojector. Accordingly, it is desired, to effectively suppress and/orcontrol corner peak radiation, i.e. intensity of outermost light raysdefining the edges and/or perimeter of a projected light pattern.

Various embodiments described herein, relate to a lens cap that can beused along with a light pattern projector. In this regard, the lens capis adapted to be engaged mechanically over a lens assembly of the lightpattern projector. The lens cap has an elliptically shaped aperturedefined through a portion of its body, that facilitates ‘vignetting’(i.e. fading/reducing intensity) of a light pattern projected by theoptical projector, while the lens cap is engaged over the light patternprojector and as the light pattern passes through the aperture of thelens cap. The projected light pattern, for example, may be structuredlight or light in coded form emitted from a light source of theprojector, via a masking element, and through a lens assembly.

To this extent, a light pattern projector when used along with the lenscap, allows outputting optical radiation defining the light pattern withhigh output power, while still meeting laser safety standards. In anaspect, the lens cap is designed to be engaged mechanically to a lensassembly of the light pattern projector by using adhesives or based onsnap-fit type arrangement. In some embodiments described herein, thelens cap has a cylindrical casing shaped back portion. As mentioned, abody of the lens cap defines an elliptically shaped aperture whichextends through the lens cap from the back surface of the lens cap tothe front surface of the lens cap. To this extent, a cross-section ofthe elliptically shaped aperture taken perpendicular to a center axis ofthe lens cap is such that, it defines a see-through type opening,through which the light pattern defined by projected rays of light maycross through when the lens cap is mechanically engaged over the lightpattern projector.

In accordance with various embodiments described herein, theelliptically shaped aperture of the lens cap is chamfered towards itsperiphery, as the elliptically shaped aperture extends from the backsurface to the front surface of the lens cap. For example, the peripheryof the elliptically shaped aperture on the back surface of the lens capmay be chamfered and/or sloped toward the center of the aperture. Thischamfered structure of the elliptically shaped aperture causes thevignetting of the light pattern, for example, the structured light as itis projected out through a lens assembly of the optical projector andfurther through the elliptically shaped aperture of the lens cap.Vignetting the projected light pattern causes reduction in intensity ofthe outermost rays of light defining a profile of the light pattern. Forexample, the chamfered structure causes the light intensity at edges ofthe light pattern to be reduced without affecting the light intensity atthe center of the light pattern projected by the light patternprojector. Thus, the vignetting of the projected light pattern causesthe output from the optical projector to meet the correspondingstandards of laser safety.

Thus, without reducing the overall output power at which an opticalprojector projects a light pattern, the optical projector may bemodified to provide a structured light pattern configured for projectiononto a flat surface and having edges that are in accordance with lasersafety standards evaluated on spherical surface. The solution providedby various embodiments of the present invention is cost-effective andsimple to design, manufacture, and incorporate into the opticalprojector. For example, the solution provided by various embodiments ofthe present invention provide for the reduction in intensity of opticalradiation/laser rays (particularly ones which are at periphery orcorners of a projected laser beam defining a pattern) without modifyingthe internal structure or lens assembly of the optical projectors.Further, by using the lens cap, as described herein, particularly inimaging systems used for dimensioning objects, there is no performancedegradation in terms of reduced power illumination for dimensioning ofthe objects, as vignetting in the light pattern is achieved at thecorner regions of the light pattern such that the central portion of thelight pattern is not affected or modified. Having described an exampleembodiment at a high level, the design of the various devices performingvarious example operations is provided below.

FIG. 1 schematically depicts an exemplary environment including a lightpattern projector, in accordance with some embodiments described herein.In an environment, according to various embodiments described herein, alight pattern projector 100 may be configured to project a light pattern102, in a field of view 104. In this regard, the light pattern 102projected by the light pattern projector 100 may be in the form ofstructured light or coded via passage through a masking filter, todefine a pattern. In one embodiment, the light pattern projector 100 mayinclude a high-power light source, for example, a vertical-cavitysurface-emitting laser (VCSEL) laser source or laser diode (not shownherein), along with a pattern masking element (not shown herein), forprojecting a structured light (i.e. a pattern of light or opticalradiations in coded form) on an object 106. To this extent, inaccordance with various embodiments, the light pattern projector 100 mayproject the light pattern 102 via the light source, through a lensassembly (not shown herein) of the light pattern projector 100. In thisregard, in accordance with various embodiments described herein, a lenscap may be positioned in front and mechanically engaged over the lensassembly of the light pattern projector 100 such that, the projectedlight pattern 102, through the lens cap assembly, passes further throughan aperture of the lens cap 108.

The light pattern projector 100, as illustrated herein, may be adaptedto output optical radiations (for example, a laser beam) defining thelight pattern 102 with various levels of intensity based on arequirement of an illumination and/or depending upon lightningconditions in the environment. Having described an environment includingthe light pattern projector 100 at a high level, various details of anexample structure of the lens cap and its assembling with respect tolight pattern projector 100 including its components are described ingreater details, in reference to FIGS. 4-13.

FIG. 2 schematically depicts an imaging system including a light patternprojector, in accordance with some example embodiments described herein.As illustrated, in accordance with some embodiments, an imaging system200, for example, but not limited to, an object dimensioner, may includea light pattern projector 202 for projecting a light pattern 204 in itsfield of view 206. In this aspect, the light pattern projector 202 mayinclude a light source, for example, but not limited to, a laseremitter, VCSEL, or a laser diode, which emits optical radiation in theform of a laser beam formed of multiple laser rays of defined intensity.The projected laser beam from the light source may pass via one or morefilters or masking elements, for example, but not limited to, a binarymask, that converts the projected laser beam into a light pattern.

In an aspect, the light pattern may represent a structured light that isprojected out from a lens assembly (not shown herein) of the lightpattern projector. In this aspect, the projected light pattern 204 maybe defined by multiple laser rays of a defined intensity that travel outfrom the light pattern projector 202. To this extent, the light patternprojector 202 may be adapted to project the light pattern 204 that isdistributed uniformly when the pattern 204 is incident on a surface, forexample, a plane surface of an object. In an aspect, three circlesmarked as 203-1, 203-2, and 203-3, in front of the light patternprojector 202, are representative of peak radiations of laser rays thatdefines the light pattern 204. These three circles 203-1, 203-2, and203-3 marked as peak radiations are also representative of portion ofprojected light rays which exceeds laser eye safety limits when thelight pattern projector 202 is used in absence of a ‘lens cap’,described in accordance with various embodiments, hereinafter throughoutthe description.

As illustrated, the imaging system 200 may also include, an imaging unitthat is adapted to capture images of an environment in its field of view210. In an example embodiment, the imaging unit includes one or morecamera units, such as, for example, a range camera 208-2 and a colorcamera 208-1, along with a processor. In this regard, in some cases, therange camera 208-2 may include, an image sensor adapted to sense areflection of the projected light pattern 204 in its field of view 210.In some examples, the range camera 208-2 may also capture an image of anobject on which the light pattern 204 may be projected, to determinedepth and three-dimensional (3D) co-ordinates of various points on theobject. Illustratively, in accordance with said embodiments, the lightpattern 204 projected by the light pattern projector 202 may be biased(212) towards the field of view 210 of the range camera 208-2, so thatthe image sensor of the range camera 208-2 effectively senses thereflection of the projected light pattern 204 in its field of view.

FIG. 3 illustrates another exemplary environment, depictingimplementation of an imaging system including the light patternprojector on which a lens cap can be mechanically engaged, in accordancewith some example embodiments described herein. As illustrated, in anenvironment 300, for example, a material handling environment like, butnot limited to, warehouses, distribution and/or shipping centers etc.,may include the imaging system 200 that may be mounted on a mountingunit 302. For example, the imaging system 200 may represent a fixedmounted dimensioner device that may be mounted at a location (forinstance, the mounting unit 302) above a conveyor system, in a materialhandling environment for measuring dimensions of packages (like cartons,boxes, consumer goods, and/or the like) as these packages pass throughand are processed for transportation on the conveyor system.

Usually, in such environments, the imaging system 200 is installed at adefined height depending on various factors, for example, a range of theimage sensor of the one or more cameras in the imaging system 200, ordistance to a platform on which the object is to be dimensioned. To thisextent, in one embodiment, the imaging system 200 may be mounted on themounting unit 302 at such a height, for example 1.5 m from a referencesurface, so that, a light pattern projector (not shown) may illuminate asurface 304 in its field of view 306, by projecting a light pattern anda camera unit (not shown) of the imaging system 200 may sense areflection of the projected light pattern in its field of view 308.Illustratively, the light pattern may be projected on an object 310 thatmay be placed at a defined platform 312, for example, but not limitedto, a weight scale. In this regard, the camera unit of the imagingsystem 200 may be initially calibrated for a reference surface, forinstance, the platform 312 on which various objects are to be placed fordimensioning.

In accordance with one embodiment, the imaging system 200 may be adaptedto compute dimensions of the object 310, in an instance, when the objectis placed on the platform 312. In this regard, the object 310 may bepositioned on the platform 312 such that a center of the object 310 isat a defined distance, for example, 1.05 m, to the imaging system 202 inthe field of view 308 of its camera unit. In this aspect, to compute thedimensions of the object 310, firstly, the light pattern projecting unitof the imaging system 200 may illuminate the object 310 by projectingthe light pattern (e.g., structured light) on the object 310 andsecondly, the camera unit may capture an image of the object 310 alongwith the projected pattern to determine various 3D points on the surfaceof the object 310 and may further compute a range image of the object310. Accordingly, the imaging system 200 may process the range image ofthe object to generate a 3D point cloud encompassing various 3D pointson surfaces of the object 310. The 3D point cloud may be furtherprocessed to compute dimensions of the object 310. Further details ofcomputing the dimensions of object using an imaging system with a lightpattern projector that projects structured light on the object aredescribed in U.S. patent application Ser. No. 16/014,851, filed Jun. 21,2018, entitled, “METHODS, SYSTEMS, AND APPARATUSES FOR COMPUTINGDIMENSIONS OF AN OBJECT USING RANGE IMAGES”, the entire contents ofwhich are incorporated by reference herein.

FIG. 4 schematically illustrates an exploded perspective view of a lightpattern projector 400, for example, the light pattern projectors 100 or200 as described in reference to FIGS. 1 and 2 respectively. In variousembodiments, a light pattern projector 400 is an example of an opticalprojector with which a lens cap of the present invention may be usedand/or secured to. In this regard, the light pattern projector 400 isadapted to be mechanically engaged with a lens cap, for instance, thelens cap 108, in accordance with various example embodiments describedherein. Structural details of the lens cap 108 are described inreference to FIGS. 4-9. As illustrated, the light pattern projector 400may include a light source 402, for instance, VCSEL board having asemi-conductor laser diode of vertical-cavity surface-emitting lasertype. In this regard, the light source may be adapted to emit opticalradiation, of varying intensity, for instance ranging from about 100Watts/cm̂2 to about 300 Watts/cm̂2 with a center wavelength of 850 nm. Inthis aspect, in an example, the VCSEL based light source 403 may includean emitter area of 3.0 mm*2.3 mm and an application output from theVCSEL board may be from about 7 Watts to 20 Watts. In accordance withvarious embodiments, when assembling components of the light patternprojector 400, the light source 402 may be affixed to a projector heatsink 404 via a thermal conductive paste 406. Further, the light source402 may be engaged to a masking element 408, for example, a patternmask, via a VCSEL adhesive 410. The masking element 408, as illustrated,may be sandwiched between a mask adhesive 412 and the VCSEL adhesive410. In this aspect, the masking element 408 may be adapted to convertthe optical radiation (laser beam) emitted from the light source 402into a light pattern, for instance, structured light. To this extent, insome examples, the masking element 408 may be binary pattern masks whichmay generate the pattern of a required energy distribution, as a laserbeam generated from the light source 402, is incident on the maskingelement 408. Illustratively, the pattern projector 400 may include amask holder 414, within which a configuration of the masking element 408and the light source 402 (formed using the mask adhesive 412 and theVCSEL adhesive 410) may be recessed and affixed on the projector heatsink 404, via the thermal conductive paste 406. Further, the mask holder414 may be adapted to be mechanically engaged with the projector heatsink 404 via one or more screws 416.

In accordance with various embodiments, the light pattern projector 400may include a projector lens assembly 418, including a projector lensthat may be engaged to the masking holder 414 via a focusing adhesive420. In this regard, the projector lens assembly 418 may include one ormore features 422 (like, but not limited to, threadings, protrusions,projections, grooves, flanges and/or the like) on its surface whichenables mechanical engagement of a lens cap over the projector lensassembly 418. Further details of engagement of the lens cap over theprojector lens assembly 418 are described in FIGS. 5, 7A, 7B, 8 and 9.

FIG. 5 schematically illustrates an arrangement 500 representing a lenscap that is mechanically engaged to a projector lens assembly of a lightpattern projector, in accordance with one example embodiment describedherein. As illustrated, a lens cap 502 is mechanically engaged over aprojector lens assembly 504 of a light pattern projector (not showncompletely herein). The projector lens assembly 504, as illustratedherein, may correspond to the projector lens assembly 418 as describedin FIG. 4. The lens cap 502, in an embodiment, may be engaged or affixedover the projector lens assembly 504 using an adhesive element 506, forexample, a UV adhesive, upon positioning the lens cap 502 over theprojector lens assembly 504. In this regard, for engaging the lens cap502 over the projector lens assembly 504, the lens cap 502 may bepositioned over the projector lens assembly 504 such that, a bezel 510of the lens cap 502 matches to a bezel 512 of the projector lensassembly 504. Further, as illustrated, a body of the lens cap 502 on itsfront surface defines an elliptically shaped aperture 508 that extendsfrom a back surface of the lens cap 502 and to the front surface of thelens cap 502.

Accordingly, to engage the lens cap 502 over the projector lens assembly504, the elliptically shaped aperture 508 of the lens cap 502 may bealigned to match an aperture defined by the bezel 512 and/or a lens ofthe projector lens assembly 504. Also, in accordance with saidembodiment, the lens cap 502 may be mechanically disengaged from theprojector lens assembly 504 (refer to lens cap as illustrated in FIG.6), based on removing the adhesive element 506 and pulling of the lenscap 502. As illustrated, the projector lens assembly 504 may be a partof a light pattern projector unit, similar to light pattern projector400, as illustrated in FIG. 4. To this extent, the projector lensassembly 504 may be engaged within a housing formed by a masking holder514, similar to the masking holder 404 as described in FIG. 4.

In accordance with various embodiments described herein, the lens cap502 may be mechanically engaged over the projector lens assembly 504such that, the light pattern projected out from a lens of the projectorlens assembly 504 passes through the elliptically shaped aperture 508 ofthe lens cap 502. Further details of a path of optical radiation, i.e.laser beam and/or light pattern as projected from a light patternprojector, via the projector lens assembly 504 and through the lens cap502 is described in reference to FIGS. 14A-E.

FIG. 6 schematically illustrates front and back surfaces of a lens cap,in accordance with one example embodiment described herein. Asillustrated, a lens cap 600 (similar to the lens cap 502 as illustratedin FIG. 5) includes a front surface 602 a and a back surface 602 b. Inthis regard, the back surface 602 b is adapted to be engagedmechanically over a surface of a light pattern projector, for instance,over the projector lens assembly 504 using the adhesive element 506 (asillustrated in FIG. 5). To this extent, the back surface 602 b of thelens cap 600 may be of a shape complimentary to a bezel surface of theprojector lens assembly 504, so that upon engaging the lens cap 600 overthe projector lens assembly 504, the back surface 602 b is mechanicallyengaged and/or secured over the projector lens assembly 504 by supportof the adhesive element 506. In this regard, in accordance with someembodiments, the back surface 602 b of the lens cap 600 may also includeadhesive slots 604-1 and 604-2 over which the adhesive element 506, suchas UV adhesive may be applied for fixing the lens cap 600 over the lenscap assembly 504. In various embodiments, the adhesive slots 604-1 and604-2 may be configured to align with corresponding bezels of theprojector lens assembly 504 such that the major axis (or the minor axisin one embodiment) of the elliptically shaped aperture 508 is alignedwith an axis of the light projector that is parallel to a line definedthe light pattern projecting unit 400 and the camera units 208.

In accordance with various embodiments described herein, a body of thelens cap 600 including the front surface 602 a of the lens cap 600defines an elliptically shaped aperture 606 which extends from the frontsurface 602 a through to the back surface 602 b of the lens cap 600,thereby creating a see-through type elliptical opening through the bodyof the lens cap 600. In this regard, a periphery of the ellipticallyshaped aperture 606 is chamfered 608 as the periphery of theelliptically shaped aperture 606 extends out from the back surface 602 bto the front surface 602 a of the lens cap 600. In this aspect, a slopeof the chamfered 608 portion of the elliptically shaped aperture 606 maybe defined based on at least one of: (i) an axial distance between asurface of the lens assembly, (for example, the projector lens assembly418 of the light pattern projecting unit 400 as illustrated in FIG. 4)and the back surface 602 b of the lens cap 600 and (ii) a desired cornerreduction ratio (e.g., to what extent and/or severity the edges and/orcorner of the light pattern is to be vignetted and/or reduced).

In this aspect, in an instance while the lens cap 600 is mechanicallyengaged over the lens assembly (like the projector lens assembly 418)light emitted from a light source (for example, the light source 402) isprojected out as a light pattern or structured light, from the projectorlens assembly 418 of the light pattern projector 400. The projectedlight pattern further travels to pass through the elliptically shapedaperture 606 of the lens cap 600. In this regard, a desired cornerreduction ratio may represent a percentage decrease in intensity ofoutermost rays of a laser beam defining the projected light pattern, asthe light pattern is projected out from the elliptically shaped aperture606 of the lens cap 600. In this aspect, the decrease in the intensityof the outermost rays of light defining the light pattern is based onblocking portions of these rays, as these rays pass along the chamfered608 portion at the periphery of the elliptically shaped aperture 606.Thus, a slope of the chamfered periphery of the elliptically shapedaperture 606 causes vignetting of the outermost rays of projected laserbeam defining the projected pattern, details of which are furtherdescribed in reference to FIGS. 11A, 11B, 12A, and 12B.

In various embodiments, the lens cap 108 comprises an aperture platehaving the elliptically shaped aperture 606 there-through. In variousembodiments, the aperture plate is circular, elliptical, a circle cutalong one or more chords, and/or another shape. In various embodiments,the lens cap 108 further comprises a cylindrically shaped back casing.For example, FIG. 7A schematically illustrates another embodiment,representing an arrangement 700 a of a lens cap 702 having acylindrically shaped back casing. As illustrated, the lens cap 702 ismechanically engaged over a projector lens assembly 704 of a lightpattern projector (not shown herein). FIG. 7B schematically illustrates,an arrangement 700 b representing the lens cap 702 that is mechanicallydis-engaged to the projector lens assembly 704, in accordance withanother example embodiment described herein. The projector lens assembly704, as illustrated herein, may correspond to a portion of a housingformed by a masking holder 710 (similar to the masking holder 404 asillustrated in FIG. 4 that includes various components of the lightpattern projector 400). Unlike the lens cap 502 and 600 as illustratedin FIGS. 5 and 6 respectively, the lens cap 702 as illustrated in FIGS.7A and 7B, includes a back portion that extends outwards from a frontsurface 706 of the lens cap, thereby defining a cylindrically shapedcasing 708. In this aspect, while engaging the lens cap 702 over theprojector lens assembly 704, the cylindrically shaped casing 708 mayrecess an aperture 714 of the projector lens assembly 704. To thisextent, the cylindrically shaped casing 708 may be mechanically engagedover the projector lens assembly 704 based on one or more featurespresent on the projector lens assembly. For example, in one example, theprojector lens assembly 704 on its surface may include one or morespiral threadings 712 which may facilitate engagement of the lens cap702 over the projector lens assembly 704. In this regard, thecylindrically shaped casing 708 of the lens cap on its internal surfacemay include threadings of shape complimentary to the threadings 712, sothat the lens cap 702 may be fastened over the aperture 714 of theprojector lens assembly 704.

In another embodiment, the lens cap 702 may be engaged over the aperture714 of the projector lens assembly 704, based on a snap fit arrangement.In this regard, the cylindrically shaped casing 708 of the lens cap 702may include, on its internal lateral surface, one or more flanges,protrusions, or grooves (see e.g., FIG. 13). Accordingly, the aperture714 of the projector lens assembly 704 may include features ofcomplimentary shape, i.e. one or more flanges, protrusions, or groovesrespectively, for mechanically engaging the lens cap 702 over theprojector lens assembly 704 in a snap-fit manner and in an appropriatealignment with respect to the projector lens assembly 704.Alternatively, in another embodiment, the lens cap 702 may be affixedover the projector lens assembly 704 by fastening the cylindricallyshaped casing 708 of the lens cap 702 over the aperture 714 while anadhesive is applied over the aperture 714.

In accordance with said embodiment, similar to the elliptically shapedaperture 508 and 606, as described in reference to FIGS. 5 and 6respectively, a body of the lens cap 702 also includes an ellipticallyshaped aperture 716 such that, a periphery of the elliptically shapedaperture 716 is chamfered, as the periphery of the elliptically shapedaperture 716 extends out from a back surface to a front surface of thelens cap 702. Further, details pertaining to the chamfered portion ofthe elliptically shaped aperture 716 are described in reference to FIG.10.

FIG. 8, in reference with FIGS. 7A and 7B, schematically illustrates afront view of an arrangement 800 depicting the lens cap 702 mechanicallyengaged over the projector lens assembly 704 of a light patternprojector, in accordance with another example embodiment describedherein. As illustrated from the front view of an engagement of the lenscap 702 over the projector lens assembly 704, the lens cap 702 on itsfront surface defines an elliptically shaped aperture 716. Theelliptically shaped aperture 716, as illustrated herein, is engaged overthe projector lens assembly 704 in such a manner, that a cross-sectionof the elliptically shaped aperture 716 taken perpendicular to a centralaxis of the lens cap 702 (e.g., the size and/or shape of theelliptically shaped aperture 716) is adapted to match a field of view ofthe light pattern projector and further to an aperture of the projectorlens assembly 704, as the lens cap 702 is mechanically engaged over theprojector lens assembly 704. In accordance with various embodiments, thelens cap 702 herein may also correspond to the lens cap 502 asillustrated in FIG. 5.

Illustratively, the elliptically shaped aperture 716 may be defined onat least a portion of the front surface of the lens cap 702 such that, acenter axis AA′ that passes orthogonally through the front surface andthe back surface of the lens cap 702, and via a point of intersection ofa major axis PQ and a minor axis MN of the elliptically shaped aperture716 is spatially offset from a central axis XX′ of the lens cap 702. Inthis aspect, in accordance with some embodiments, a length of the majoraxis PQ and a length of the minor axis MN, of the elliptically shapedaperture 716 is based on a defined value to which a light patternprojector including the projector lens assembly 704 projects a lightpattern that is offset from a center axis of a lens of the projectorlens assembly 704. Illustratively, the projector lens assembly 704 alongwith its housing may include various components on a printed circuitboard (PCB) arrangement 802 like a light source, a masking element, aheat sink, etc. (like components 404-420 as illustrated and described inFIG. 4) of an optical projector. The projector lens assembly 704 may beconfigured to provide a light pattern that is centered at a point thatis offset from the center axis of the lens of the projector lensassembly 704 such that the light pattern is provided in the field ofview of associated imaging units. The point of intersection of the majoraxis PQ and the minor axis MN of the elliptically shaped aperture 716 issimilarly spatially offset from the central axis XX′ of the lens cap702.

FIG. 9, in reference to FIGS. 7A and 7B, illustrates a side view 900 ofthe lens cap 702 mechanically engaged over the projector lens assembly704 of the light pattern projector 710, as described in reference toFIG. 7. As illustrated, the lens cap 702 defines the elliptically shapedaperture 716 that is chamfered towards a periphery defined by ellipticalends of the aperture. In accordance with some embodiments, in operation,while the lens cap 702 is engaged over the projector lens assembly 704,the elliptically shaped aperture 716 may be adapted to at least block orpartially block the outermost rays (e.g., the light rays that are atperiphery of a projected laser beam 904 defining the light pattern asgenerated by a light source 902 and projected from the projector lensassembly 704) from passing through the elliptically shaped aperture 716of the lens cap 702. For example, the elliptically shaped aperture 716and the chamfered periphery and/or edge thereof may be configured tocause a vignetting effect on the light pattern. In an exampleembodiment, a vignetting effect is a softening or reducing in theintensity of light pattern about the periphery or edges of the lightpattern.

FIG. 10 schematically illustrates multiple views 1000 a, 1000 b, 1000 c,and 1000 d, representing different surfaces of a lens cap 1000, inaccordance with various embodiments described herein. As illustrated,1000 a represents a perspective view of a front body the lens cap 1000,depicting a front surface 1002 of the lens cap 1000 and a cylindricallyshaped casing 1004 of the lens cap 1000 that extends out and/orbackwards from the front surface 1002 of the lens cap 1000, therebyforming a back portion of the lens cap 1000. As illustrated, a portionof the front surface 10002, defines an opening in the form of anelliptically shaped aperture 1008 that extends from a back surface ofthe lens cap 1000 through the front surface 1002 of the lens cap 1000thereby forming a see-through type opening. As illustrated, an apertureof the elliptically shaped aperture 1008 through the lens cap 1000 issuch that, a center axis 1010 of the elliptically shaped aperture 1008is offset by a distance ‘D’ to a central axis 1012 of the lens cap 1000.In this regard, the center axis 1010 of the elliptically shaped aperture1008 of the lens cap 1000 represents an axis passing orthogonallythrough the front surface 1002 and the back surface (refer to 1014 inview 1000 b) of the lens cap 1000 and passing through a point ofintersection ‘A’ of a major axis and minor axis of the ellipticallyshaped aperture 1008. The central axis 1012 of the lens cap 1000 hererepresents an axis passing orthogonally through the front surface 1002and the back surface 1014 the lens cap 1000 via point of center of thelens cap 1000. For example, if the lens cap 1000 is circularly shaped,the central axis 1012 is an axis passing through a point of intersectionof two diameters drawn on the circular shape of the lens cap 1000.

In accordance with various embodiments described herein, theelliptically shaped aperture 1008 is of a shape that is adapted to matcha field of view of the light pattern projector (e.g., the light patternprojector 400 as illustrated in FIG. 4) with the lens cap 1000 ismechanically engaged over a lens assembly of the projector (e.g., thelens assembly 412 as illustrated in FIG. 4). To this extent, an offset Dof the center axis 1010 and the central axis 1012 of the lens cap isdefined based on an offset at which the light pattern projector projectsa light pattern or a structured light.

As illustrated, 1000 b represents a perspective view of the lens cap1000 having a back surface 1014 and the cylindrically shaped casing 1004that extends out and/or back from the front surface 1002 of the lens cap1000. In this regard, in accordance with some embodiments describedherein, the back surface 1014 and the cylindrically shaped casing 1004of the lens cap 1000 together represent a back portion of the lens cap1000. As illustrated, a periphery of the elliptically shaped aperture1008 is chamfered 1016 as the elliptically shaped aperture 1008 extendsout from the back surface 1014 to the front surface 1002 of the lenscap. In this regard, the periphery of the elliptically shaped aperture1008 is chamfered for a defined slope depending on various factors. Inthis aspect, in accordance with various embodiments described herein,the slope of the chamfered 1016 along the periphery of the ellipticallyshaped aperture 1008 is defined based on an axial distance between theback surface 1014 of the lens cap 1000 to the lens assembly of the lightpattern projector when the lens cap 1000 is mechanically engaged overthe light pattern projector. For example, the slope of the chamfering1016 of the periphery of the elliptically shaped aperture 1008 isdesigned and/or determined based on the expected and/or designeddistance between the back surface 1014 of the lens cap 1000 and the lensassembly of the light pattern projector. Alternatively, or additionally,the slope may be defined based on a desired ‘corner reduction ratio’that is representative of a desired percentage decrease, in intensity ofthe outermost rays and/or edges of a projected light pattern.

As illustrated, view 1000 c represents a front view of the lens cap 1000having the elliptically shaped aperture 1008 defined on the frontsurface 1002 of the lens cap and 1000 d represents a side view of thelens cap 1000 representing a portion of the cylindrically shaped casing1004 of the lens cap 1000 that extends out and/or back from the frontsurface 1002 of the lens cap 1000.

FIGS. 11A and 11B schematically illustrates structures of a frontsurface and back surface respectively of a lens cap 1100, in accordancewith some example embodiments as described herein. Referring to FIGS.11A and 11B, as illustrated, 1100 a represents a front view of the lenscap 1100 and 1100 b represents a back view of the lens cap 1100. In thisaspect, from the front view 1100 a of the lens cap 1100, a front surface1102 of the lens cap 1100 and from the back view 1100 b of the lens cap,a back surface 1104, is illustrated. In various embodiments, a portionof the front surface 1102 defines an elliptically shaped aperture 1106which extends from the back surface 1104 through the front surface 1102of the lens cap 1100, thereby forming a see-through hollow opening. Inthis regard, the elliptically shaped aperture 1106 of the lens cap 1100is chamfered (towards its periphery) 1108 to a defined slope, about itsperiphery as the elliptically shaped aperture 1106 extends out from theback surface 1104 to the front surface 1102 of the lens cap 1100. Tothis extent, in accordance with one embodiment, as illustrated, adistance between two farthest points (P1 and P2) defined along a minoraxis ‘MR’ of the elliptically shaped aperture 1106 may be in a range4.93+/−0.02 millimeters (mm), i.e. from about 4.91 mm to about 4.95 mm.

Further, as illustrated, in accordance with said embodiment, a distancebetween two farthest points (P3 and P4) defined along the major axis‘MA’ of the elliptically shaped aperture 1106 may be in a range7.00+/−0.02 mm, i.e. from about 6.98 mm to about 7.02 mm. In thisregard, in accordance with various embodiments described herein, thedistance between the points P1 and P2 and the distance between thepoints P3 and P4 may be larger or smaller than these values, asappropriate for the application. In an example embodiment, the offsetvalue ‘D’ (referring to FIG. 10) representing an offset between a centeraxis (for example the center axis 1010) of the elliptically shapedaperture and a central axis (for example, 1012) of the lens cap 1100 maybe about 0.65+/−0.02 mm, i.e. from 0.63 to about 0.67 mm. Various otheroffset values ‘D’ may be used in various embodiments, as appropriate forthe applications. The offset ‘D’ as mention herein, may also representan offset at which the light pattern is projected from the light patternprojector, from a center axis or focus of a light source, of the lightpattern projector (e.g., the light pattern projector 400 as illustratedin FIG. 4).

In various embodiments, the back surface 1104 may comprise alignmentgrooves 1110 configured to aiding in the alignment of the lens cap 1100with the lens assembly. For example, the alignment grooves 1110 may beconfigured to aid in properly aligning the cylindrically shaped aperture1106 with the lens assembly, the light pattern projected by the lightpattern projector and/or the like. For example, the alignment grooves1110 may be configured to mate and/or engage with corresponding grooveson the housing of the lens assembly such that, when the alignmentgrooves and the corresponding grooves on the housing of the lensassembly are mated and/or engaged, the cylindrically shaped aperture1106 is aligned with the lens assembly to provide the desired vignettingeffect.

FIGS. 12A and 12B schematically illustrates structures of a frontsurface and back surface respectively of a lens cap 1200 having acylindrical casing shaped back portion, in accordance with some exampleembodiments as described herein. Referring to FIGS. 12A and 12B, asillustrated, 1200 a represents a front view of the lens cap 1200 and1200 b represents a back view of the lens cap 1200. In this aspect, fromthe front view 1200 a of the lens cap 1200, a front surface 1202 of thelens cap 1100 and from the back view 1200 b of the lens cap, a backsurface 1204, is illustrated. Illustratively, the lens cap 1200 includesa cylindrically shaped casing 1203 that extends orthogonally outwardsand/or back from the front surface 1202 towards a back side of the lenscap 1200. In this aspect, the back surface 1204 along with thecylindrically shaped casing 1203 defines a back portion of the lens cap1200. According to various embodiments, the structure of the lens cap1200 may be correspondingly similar to a structure of the lens cap 1000as described in reference to FIG. 10.

As illustrated, a portion of the front surface 1202 defines anelliptically shaped aperture 1206 which extends from the back surface1204 to the front surface 1202 of the lens cap 1000, thereby forming asee-through hollow opening. In this regard, the elliptically shapedaperture 1206 of the lens cap 1200 is chamfered 1208 to a defined slope,about its periphery, as the aperture 1206 extends through from the backsurface 1204 to the front surface 1202 of the lens cap 1200. To thisextent, in accordance with one embodiment, as illustrated, a distancebetween two farthest points (A1 and A2) defined along a minor axis ‘MR’of the elliptically shaped aperture 1206 may be in a range 5.43+/−0.05millimeters (mm), i.e. from about 5.38 mm to about 5.48 mm. Further, asillustrated, in accordance with said embodiment, a distance between twofarthest points (B1 and B2) defined along the major axis ‘MA’ of theelliptically shaped aperture 1206 may be in a range 7.50+/−0.05 mm, i.e.from about 7.45 mm to about 7.55 mm. In this regard, in variousembodiments, the distance between the points A1 and A2 and the distancebetween the points B1 and B2 may be of various ranges, as appropriatefor the application (e.g., based on the field of view of the imagingunits, distance to an object to be imaged, the light pattern, and/or thelike). In an example embodiment, the offset value ‘D’ (referring to FIG.10) representing an offset between a center axis (for example the centeraxis 1010) of the elliptically shaped aperture 1206 and a central axisXY of the lens cap 1200 may be about 0.65+/−0.02 mm, i.e. from 0.63 toabout 0.67 mm. Various other offset values ‘D’ may be used in variousembodiments, as appropriate for the applications. The offset ‘D’ asmention herein, may also represent an offset at which the light patternis projected from the light pattern projector, from a center axis orfocus of a light source, of the light pattern projector (e.g., the lightpattern projector 400 as illustrated in FIG. 4). Further details relatedto projecting the light pattern with an offset is described in FIGS.14A-14E.

FIG. 12C schematically illustrates a side view 1200 c of the lens cap1200 having the cylindrically shaped casing 1203 that extends from afront surface 1202 of the lens cap 1200. As illustrated, in accordancewith some example embodiments, a width of the front surface 1202 as itextends from a portion of the cylindrically shaped casing 1203 may be ofabout 0.5 mm.

FIG. 13 schematically illustrates use of alignment features formechanically engaging a lens cap over a lens assembly of a light patternprojector, in accordance with some embodiments described herein. Inparticular, proper alignment of the elliptically shaped aperture of thelens cap with the light pattern projected by the light pattern projectorallows the lens cap to effectively reduce the intensity of the lightpattern about the edges and/or periphery of the light pattern withoutdiminishing the efficacy of the light pattern for the application (e.g.,dimensioning objects and/or the like). Illustratively, an arrangement1300 includes, a lens cap 1302 that is mechanically engaged over a lensassembly 1304 of an optical projector (for example, the light patternprojector 400 as described in FIG. 4). In this regard, an alignmentfeature assembly 1306, as illustrated herein, may be used formechanically engaging the lens cap 1302 over an aperture 1308 of thelens assembly 1304. To this extent, the alignment feature assembly 1306may include one or more features 1310, like, but not limited to,flanges, projections, bezels, or grooves, as illustrated herein, thatmay be adapted to hold the lens cap 1302 and further align an aperture,for instance, the elliptically shaped aperture 1106 as illustrated inFIGS. 11A or 11B, of the lens cap 1100 with an aperture, light path,and/or field of view defined by a lens of the lens assembly 1304. Theone or more features 1310, in this regard, may also be adapted tofacilitate the lens cap 1302 to be recessed within a seat defined by ahousing of the alignment feature assembly 1306. In an exampleembodiment, the alignment feature assembly 1306 is used to secure thelens cap 1302 to the lens assembly 1304 (e.g., over the aperture 1308)with appropriate alignment of the cylindrically shaped aperture of thelens cap 1302 with the lens assembly 1304, field of view of the lightpattern projector, the light pattern projected by the light patternprojector, and/or the like. In an example embodiment, after the lens cap1302 has been secured to the lens assembly 1304 with the appropriatealignment, the alignment feature assembly 1306 is removed.

Illustratively, the alignment feature assembly 1306 has two faces, i.e.a front face A and a back-face B. In this aspect, for engaging the lenscap 1302 over the lens assembly 1304, the lens cap 1302 may be recessedthrough a first surface into an aperture 1312 defined by the housing ofthe alignment feature assembly 1306. As the lens cap is seated orrecessed into the aperture 1312, the alignment feature assembly 1306including the lens cap 1302 may be engaged mechanically over theaperture 1308 of the lens assembly 1304 such that, a surface of the lensassembly 1304 defining the aperture 1308 mates with the back-surface Bof the alignment feature assembly 1306. Further, the alignment featureassembly 1306 may be rotated either clockwise or anti-clockwise, forsnapping-on or sealing-up the lens cap 1302 over the aperture 1308 ofthe lens assembly 1304 and for aligning apertures of the lens cap 1302and the lens assembly 1304 respectively. In accordance with someembodiments, an arrangement including a thread engagement may be definedon one or more of (a) lens cap 1302, (b) the alignment feature assembly1306, and/or (c) the aperture 1308 of the lens assembly 1304, formechanically loading the lens cap 1302 over the lens assembly 1304. Tothis extent, the aperture 1308 of the lens assembly 1304 may include,one or more threadings 1314 along with threadings on at least one of thelens cap 1302 and the alignment feature assembly 1306 that complimentsthe threadings on the aperture 1308, for mechanically engaging the lenscap 1302 over the lens assembly 1304. Additionally, or alternatively, inaccordance with various embodiments described herein, the alignmentfeature assembly 1306 may also be adapted for aligning apertures (forinstance, the elliptically shaped apertures 1106 and 1206, asillustrated and described in FIGS. 11A, 11B, 12A, and 12B) of the lenscap 1302 with the aperture 1308 of the lens assembly 1304.

FIGS. 14A and 14B schematically illustrate cut-away perspective views1400 a and 1400 b of a light pattern projector 1402 having a lens cap1403 mechanically engaged over a lens assembly 1404 of the light patternprojector 1402. Further, FIGS. 14D and 14E schematically illustrateperspective views of the lens cap 1403 having an elliptically shapedaperture 1410 that is mechanically engaged over the light patternprojector 1402. In this regard, the light pattern projector 1402 withthe lens cap 1403 engaged to it, is adapted to project the light pattern1406 that is spatially offset in the direction 1408 with respect an axisof a lens assembly of the light pattern projector, in accordance withsome example embodiments described herein. Illustratively, the lightpattern projector 1402 projects a light pattern 1406 that is spatiallyoffset in one direction 1408, with respect a central axis XX′ of thelens assembly 1404 of the light pattern projector 1402, in accordancewith some example embodiments described herein. In various embodiments,the central axis XX′ of the lens assembly 1404 aligns with the centralaxis of the lens cap 1403 (see e.g., FIG. 10). As illustrated, the lightpattern 1406 (or structured light) is projected out from a lens of thelens assembly 1404 (e.g., similar to as described with regard to theprojector lens assembly 418 illustrated in FIG. 4) such that the lightpattern 1406 is spatially offset towards the direction 1408. In thisaspect, in accordance with various embodiments described herein, theoffset in the projected light pattern 1406 may correspond to the offsetvalue ‘D’ between the axis XX′ of a lens of the lens assembly 1404 and acenter axis AA′ of an elliptically shaped aperture defined by the lenscap 1403. In this regard, the center axis AA′ of the elliptically shapedaperture represents an axis passing through a point of intersection ofmajor axis and minor axis of the elliptically shaped aperture, asdescribed in FIGS. 8, 10, 11A, 11B, 12A, and 12B respectively. Forexample, in various embodiments, the offset value ‘D’ between thecentral axis of the lens cap and the center axis of the ellipticallyshaped aperture through the lens cap may be the same as the offset ‘D’between the central axis of the projector lens assembly and the centeraxis of the projected light pattern.

Here, the offset value ‘D’ in accordance with various embodimentsdescribed herein, may be depend on various factors. For example, in someembodiments, in cases, where the light pattern projector 1402 is withina housing of an imaging system, having an imaging unit (including acamera), the offset value ‘D’ may depend on (i) a parallax arrangementof a light source, masking element, and lens of the light patternprojector 1402 for generating a structured light beam, and/or (ii) anaxial separation between the lens assembly 1404 and an imaging unitwithin a housing of the light pattern projector 1402. To this extent, asshown in FIGS. 2 and 3, the light pattern 1406 is projected at theoffset value ‘D’, so that the projected pattern 1406 and/or thereflection of the projected pattern from one or more objects iseffectively sensed by an image sensor of the imaging unit of the imagingsystem. In various embodiments, when the lens cap 1403 is mechanicallyengaged over the lens assembly 1404, a central axis of overall circularbody the lens cap (similar to the central axis 1012 as described in FIG.10 or axis XX′ as described in FIG. 8) would be coaxial with the centralaxis XX' of the lens assembly 1404 as illustrated in FIGS. 14A-14C. FIG.14C schematically illustrates a side view 1400 c (similar to the sideview illustrated in FIG. 9) of the light pattern projector 1402 havingthe lens cap 1403 mechanically engaged over the lens assembly 1404 ofthe light pattern projector 1402, where the light pattern projector 1402projects the light pattern 1406 that is spatially offset in thedirection 1408 (e.g., the light pattern 1406 is not centered on thecentral axis XX′ of the lens assembly 1404 and/or the lens cap 1403), inaccordance with some embodiments. As illustrated from the side view 1400c, an elliptically shaped aperture (similar to elliptically shapedapertures 606, 716, 1008, 1106, and 1206, as illustrated and describedin FIGS. 7-12) of the lens cap 1403 towards its peripheral ends ischamfered 1410 with a defined slope. For example, referring to FIG. 14C,the elliptically shaped aperture of the lens cap 1403 has chamferedperipheral ends 1410 having a defined slope, represented by slope oflines PP′ and QQ′, as the elliptically shaped aperture extends out froma back surface to a front surface of the lens cap 1403. In this aspect,the slope of the chamfered 1410 peripheral end of the aperture may beconsistent about the perimeter of the aperture and is defined based onvarious factors. For instance, in one example, the slopes of lines PP′and QQ′ (representing the slope of the chamfered 1410 peripheral end)may be based on an axial distance between the lens assembly 1404 of thelight pattern projector 1402 and a back surface of the lens cap 1403, asin, when the lens cap 1403 is engaged over the lens assembly 1404. Also,in some examples, the slope may be based on a desired corner reductionration representative of a vignetting desired in the projected lightpattern 1406, to suppress corner peak radiation in a pattern profile ofthe light pattern 1406 and to realize controlled dark corners when thelight pattern 1406 is incident on a surface. In an example embodiment,the slop of the chamfered 1410 peripheral end of the aperture may bedifferent at various portions of the perimeter of the aperture. Forexample, the slopes of lines PP′ and QQ′ may be different. For example,PP′ may not simply be a rotation or reflection of QQ′, in an exampleembodiment.

Additionally, or alternatively, according to some embodiments, the slopeof the chamfered 1410 ends of the elliptically shaped aperture may bedefined based on analyzing results obtained after multiple simulationsand testing of the light pattern projector 1402. In this aspect, thesimulation and/or testing as mentioned may be performed to evaluate thelight pattern projector′s 1402 performance based on radiation leveldistribution over an entire field of view of the projector 1402 in orderto achieve an exact amount of vignetting required to meet laser eyesafety standards while minimizing an impact to performance of the lightpattern projector 1402 in terms of power output levels of illumination.Accordingly, the slope of the chamfered 1410 peripheral ends of theelliptically shaped aperture may be defined to generate vignetting inthe light pattern for specific locations with required corner reductionratio, as described earlier in reference to FIG. 6.

FIG. 15, schematically illustrates, vignetting of outermost rays inoptical radiation such as, a light pattern or structured light projectedby a light pattern projector, based on using a lens cap along with thelight pattern projector, in accordance with some embodiments describedherein. As illustrated, a first arrangement 1502 a depicts a trajectoryof optical radiation, for instance, structured light 1504, as it isprojected from a light source (for instance the light source 402 asillustrated in FIG. 4) of the light pattern projector, via a maskingelement 1506, in an instance, while a lens assembly 1508 of the patternprojector is used without a lens cap. A second arrangement 1502 bdepicts another trajectory of the structured light 1504, via the maskingelement 1506 of the light pattern projector, in an instance, while thelens assembly 1508 of the pattern projector is used along with a lenscap 1510.

Illustratively, as compared with the first arrangement 1502 a, referringto the second arrangement 1502 b (i.e. one with lens cap 1510) outermostrays 1514 of a projected laser beam of light defining the structuredlight 1504 are chopped off and/or at least partially blocked as thestructured light 1504 is projected out from the lens assembly 1508 andthrough the lens cap 1510. In this aspect, the intensity of theoutermost rays in the projected light beam defining the structured light1504 is reduced as the structured light 1504 travels through an aperture(for example, the elliptically shaped apertures 1106, 1206 asillustrated in FIGS. 11A, 11B, 12A, and 12B respectively) of the lenscap 1510. To this extent, the chamfered periphery (1108, 1208) of theelliptically shaped aperture of the lens cap 1510 at least partiallyblocks passage of the structured light 1504 through the aperture of thelens cap 1510, thereby causing vignetting of the structured light 1504towards corners, periphery and/or edges of the light pattern defined bythe structured light 1504. In accordance with one example implementationof said embodiments, at a standard operation of an optical patternprojector that emits 5 pulses per second via a light source, a powerlimit measured at 100 mm distance from the lens assembly 1508, where adiameter of an aperture of the lens cap is 7 mm may be 175 uw or less.In this aspect, a comparison of results obtained without using the lenscap 1510 and with using the lens cap 1510 are further illustrated inFIGS. 16A and 16B.

FIGS. 16A and 16B schematically illustrate simulation results includingresults depicting illumination of a surface with vignetting by using thelight pattern projector with a lens cap and results depictingillumination of a surface by using the light pattern projector withoutthe lens cap, in accordance with various embodiments described herein.Illustratively, 1602 depicts sample results including multiple testpattern images obtained, upon simulation of an optical pattern projectorarrangement (for instance, the light pattern projector 400, asillustrated in FIG. 4) using a lens cap, (for example, any of the lenscaps 1100 or 1200, as illustrated in FIGS. 11A, 11B, 12A, 12Brespectively). Comparatively, 1604 depicts results obtained withoutusing the lens cap. In this aspect, the results 1602 and 1604, asillustrated herein, each represent various images of a light pattern(e.g., structured light) incident on a surface of an object. Asillustrated in 1602, the brightness or saturation in the light patterntowards corners or periphery of the light pattern 1606, is suppressedand/or reduced due to vignetting of the light pattern by the lens cap(e.g., any of the lens caps 1100 or 1200, as illustrated and describedin reference to FIGS. 11A, 11B, 12A, 12B respectively). To this extent,as illustrated in one or more images of test patterns , for instance theresults 1602, using a lens cap effectively suppresses any leakagesand/or increased intensity about the corners, periphery, and/or edges ofa light pattern projected by a light pattern projector that may be abovea safety standard (e.g., laser safety standards) that are required to bemet.

In accordance with some example embodiments, a range of an offset, forinstance, the offset value ‘D’ as described in reference to FIGS. 10 and14A-14E, may be from about 0.5 mm to about 0.8 mm. Further, inaccordance with some example embodiments, with respect to ellipticallyshaped aperture on the lens cap, a range of major axis (for example themajor axis PQ or MA, as illustrated in FIGS. 8, 11A, 11B, 12A, and 12Brespectively) of the aperture may be from about 6.5 mm to about 8.00 mmand a range of minor axis (for example the minor axis MN and MR′, asillustrated in FIGS. 8, 11A, 11B, 12A, and 12B respectively) of theelliptically shaped aperture may be from about 4.93 mm to about 5.93 mmrespectively. Also, in accordance with various embodiments describedherein, the lens cap may be made up of injection molded polycarbonate(PC)-ABS material, for instance PC500 with matte surface finish.

Although the aperture through the lens cap is generally referred to asan elliptically shaped aperture herein, various other shape aperturesare considered. For example, various shape apertures (circular, square,rectangular, trapezoidal, irregular, and/or the like) may be used invarious embodiments, as appropriate for the applications and thecorresponding light patterns.

In some example embodiments, certain ones of the operations herein maybe modified or further amplified as described below. Moreover, in someembodiments additional optional operations may also be included. Itshould be appreciated that each of the modifications, optional additionsor amplifications described herein may be included with the operationsherein either alone or in combination with any others among the featuresdescribed herein.

As will be appreciated by one of skill in the art the order of steps inthe foregoing embodiments may be performed in any order. Words such as“thereafter,” “then,” “next,” etc. are not intended to limit the orderof the steps; these words are simply used to guide the reader throughthe description of the methods. Further, any reference to claim elementsin the singular, for example, using the articles “a,” “an” or “the” isnot to be construed as limiting the element to the singular.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the aspectsdisclosed herein may include a general purpose processor, a digitalsignal processor (DSP), a special-purpose processor such as anapplication specific integrated circuit (ASIC) or a field programmablegate array (FPGA), a programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but, in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Alternatively, or in addition, some steps or methods maybe performed by circuitry that is specific to a given function.

In one or more example embodiments, the functions described herein maybe implemented by special-purpose hardware or a combination of hardwareprogrammed by firmware or other software. In implementations relying onfirmware or other software, the functions may be performed as a resultof execution of one or more instructions stored on one or morenon-transitory computer-readable media and/or one or more non-transitoryprocessor-readable media. These instructions may be embodied by one ormore processor-executable software modules that reside on the one ormore non-transitory computer-readable or processor-readable storagemedia. Non-transitory computer-readable or processor-readable storagemedia may in this regard comprise any storage media that may be accessedby a computer or a processor. By way of example but not limitation, suchnon-transitory computer-readable or processor-readable media may includerandom access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), FLASH memory, diskstorage, magnetic storage devices, or the like. Disk storage, as usedherein, includes compact disc (CD), laser disc, optical disc, digitalversatile disc (DVD), floppy disk, and Blu-ray disc™, or other storagedevices that store data magnetically or optically with lasers.Combinations of the above types of media are also included within thescope of the terms non-transitory computer-readable andprocessor-readable media. Additionally, any combination of instructionsstored on the one or more non-transitory processor-readable orcomputer-readable media may be referred to herein as a computer programproduct.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of teachings presented in theforegoing descriptions and the associated drawings. Although the figuresonly show certain components of the apparatus and systems describedherein, it is understood that various other components may be used inconjunction with the supply management system. Therefore, it is to beunderstood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, the steps in the method described above may not necessarilyoccur in the order depicted in the accompanying diagrams, and in somecases one or more of the steps depicted may occur substantiallysimultaneously, or additional steps may be involved. Although specificterms are employed herein, they are used in a generic and descriptivesense only and not for purposes of limitation.

1. A lens cap having, a back surface, adapted to be mechanically engagedover a light pattern projecting unit; a front surface defining anelliptically shaped aperture on a portion of the front surface, theelliptically shaped aperture adapted to provide a vignetting on a lightpattern projected from the light pattern projecting unit, wherein aperiphery of the elliptically shaped aperture is chamfered as theelliptically shaped aperture extends out from the back surface to thefront surface of the lens cap and wherein a center axis, passingorthogonally through the front surface and the back surface of the lenscap, and via a point of intersection of a major axis and a minor axis ofthe elliptically shaped aperture, is offset from a central axis of thelens cap.
 2. The lens cap of claim 1, wherein, a cross-section of theelliptically shaped aperture is adapted to match a field of view of thelight pattern projecting unit, as the lens cap is mechanically engagedover a lens assembly of the light pattern projecting unit.
 3. The lenscap of claim 1, wherein the elliptically shaped aperture of the lens capis adapted to at least partially block outermost rays which are at aperiphery of a projected laser beam defining the projected pattern, asthe light pattern projected from a lens assembly of the light patternprojecting unit passes through the elliptically shaped aperture of thelens cap.
 4. The lens cap of claim 1, a length of the major axis and alength of the minor axis of the elliptically shaped aperture is based ona defined value to which the projected light pattern is offset from acenter axis of the lens of the light pattern projecting unit.
 5. Thelens cap of claim 1, wherein a slope of chamfered periphery of theelliptically shaped aperture is based on at least one of: (i) an axialdistance between a lens assembly of the light pattern projecting unitand the back surface of the lens cap and (ii) a corner reduction ratioof the projected pattern, wherein the corner reduction ratio isrepresentative of a desired percentage decrease, in intensity ofoutermost rays of a projected laser beam defining the projected lightpattern.
 6. The lens cap of claim 1, wherein a slope of chamferedperiphery of the elliptically shaped aperture causes vignetting ofoutermost rays of projected laser beam defining the projected patternand wherein an offset in the center axis of the elliptically shapedaperture is to match an offset of the projected light pattern projectedby a light source through a lens of the light pattern projecting unit.7. The lens cap of claim 1, wherein a length the major axis of theelliptically shaped aperture is in a range from about 6.5 mm to about8.0 mm and wherein a length of the minor axis of the elliptically shapedaperture is in a range from about 4.93 mm to about 5.93 mm.
 8. A lenscap having, a back surface adapted to be mechanically engaged over alight pattern projecting unit that is adapted to project a structuredlight; a front surface defining an elliptically shaped aperture, on aportion of the front surface, the elliptically shaped aperture adaptedto provide a vignetting on the structured light projected from the lightpattern projecting unit.
 9. The lens cap of claim 8, wherein theelliptically shaped aperture is chamfered towards a periphery at whichthe elliptically shaped aperture extends out from the back surface tothe front surface of the lens cap and wherein a center axis, passingorthogonally through the front surface and the back surface and via apoint of intersection of a major axis and a minor axis of theelliptically shaped aperture, is offset from a central axis of the lenscap.
 10. The lens cap of claim 8, wherein, a cross-section of theelliptically shaped aperture is adapted to match a field of view of thelight pattern projecting unit, as the lens cap is mechanically engagedon a lens assembly of the light pattern projecting unit.
 11. The lenscap of claim 8, wherein the elliptically shaped aperture of the lens capis adapted to at least, block or partially allow, outermost rays whichare at periphery of a projected laser beam defining the structuredlight, as the structured light projected from a lens assembly of thelight pattern projecting unit passes through the elliptically shapedaperture of the lens cap.
 12. The lens cap of claim 8, a length of themajor axis and a length of the minor axis of the elliptically shapedaperture is based on a defined value to which the projected structuredlight is offset from a center axis of the lens of the light patternprojecting unit.
 13. The lens cap of claim 8, wherein a slope ofchamfered periphery of the elliptically shaped aperture is based on atleast one of: (i) an axial distance between a lens of the light patternprojecting unit and the back surface of the lens cap and (ii) a cornerreduction ratio of the projected pattern, wherein the corner reductionratio is representative of a desired percentage decrease, in intensityof outermost rays of a projected laser beam defining the structuredlight.
 14. The lens cap of claim 8, wherein a slope of chamferedperiphery of the elliptically shaped aperture causes vignetting ofoutermost rays of projected laser beam defining the structured light andwherein an offset in the center axis of the elliptically shaped apertureis to match an offset of the structured light projected by a lightsource through a lens assembly of the light pattern projecting unit. 15.The lens cap of claim 8, wherein a length the major axis of theelliptically shaped aperture is in a range from about 6.5 mm to about8.0 mm and wherein a length of the minor axis of the elliptically shapedaperture is in a range from about 4.93 mm to about 5.93 mm.
 16. The lenscap of claim 8, wherein the lens cap is adapted to be engaged over thelight pattern projecting unit using at least one of, a snap fitarrangement and an adhesive.
 17. The lens cap of claim 8, wherein thelens cap is adapted to be engaged over the light pattern projecting unitusing an alignment features having a structure that is adapted to recessthe lens cap to engage the lens cap over the light pattern projectingunit and wherein the lens cap comprises threadings that are adapted tobe engaged with complimentary threadings on surface of the patternprojecting unit.
 18. The lens cap of claim 8, wherein the lens cap isformed of injection molded polycarbonate-ABS-thermoplastic and is ofthickness of about 1 mm and wherein the thickness of chamfered peripheryof the elliptically shaped aperture is of thickness of about 0.5 mm. 19.An imaging system comprising: a light pattern projecting unit comprisinga projector lens assembly, the light pattern projecting unit adapted toproject structured light in a field of view of the light patternprojecting unit; and a lens cap having, a back surface adapted to bemechanically engaged over the projector lens assembly of the lightpattern projecting unit; and a front surface defining an ellipticallyshaped aperture, on a portion of the front surface, the ellipticallyshaped aperture adapted to provide a vignetting on the structured lightprojected from the light pattern projecting unit.
 20. The imaging systemof claim 19, wherein the elliptically shaped aperture is chamferedtowards a periphery at which the elliptically shaped aperture extendsout from the back surface to the front surface of the lens cap andwherein a center axis, passing orthogonally through the front surfaceand the back surface and via a point of intersection of a major axis anda minor axis of the elliptically shaped aperture, is offset from acentral axis of the lens cap.
 21. The imaging system of claim 19,wherein the elliptically shaped aperture of the lens cap is adapted toat least, block or partially allow, outermost rays which are atperiphery of a projected laser beam defining the structured light, asthe structured light projected from the projector lens assembly of thelight pattern projecting unit passes through the elliptically shapedaperture of the lens cap.
 22. The lens cap of the imaging system ofclaim 19, wherein a slope of chamfered periphery of the ellipticallyshaped aperture is based on at least one of: (i) an axial distancebetween the projector lens assembly of the light pattern projecting unitand the back surface of the lens cap and (ii) a corner reduction ratioof the projected pattern, wherein the corner reduction ratio isrepresentative of a desired percentage decrease, in intensity ofoutermost rays of a projected laser beam defining the structured light.23. The imaging system of claim 20, further comprising, an imaging unit,including an image sensor, the imaging unit adapted to capture an imageof a reflection of the structured light, sensed by the image sensor in afield of view of the imaging unit and wherein a slope of the chamferedperiphery of the elliptically shaped aperture causes vignetting ofoutermost rays of projected laser beam defining the projected structuredlight and wherein an offset in the center axis of the ellipticallyshaped aperture is to match an offset of the projected structured lighttowards a field of view of the imaging unit.